Grapple pivot joint with swing dampener

ABSTRACT

A suspension for a grapple includes a swivel link coupled between a support boom and a head of the grapple for permitting the latter to undergo swinging movement about first and second pivot axes arranged crosswise to each other. At each pivot axis, there is a pivot pin having a brake associated therewith and including a brake housing enclosing an outer end portion of the pin and containing brake disks and a Belleville spring for maintaining the disks frictionally engaged with each other.

BACKGROUND OF THE INVENTION

The present invention relates to forestry grapples and more specificallyrelates to pivot joint structures for suspending grapples from supportbooms.

It is known to suspend grapples from support booms by means of pivotjoint structures which permit the grapple to swing about separatehorizontal axes located crosswise to each other. One problem with suchsuspensions is that when the vehicle carrying the grapple is operatedover rough terrain while the grapple is empty the grapple flops wildlyabout these axes and sometimes comes into contact with the support boomor other vehicle structure which may result in damage to the grapple,boom and/or other structure.

To overcome the problem of grapple flop, it is known in the prior art toprovide grapple pivot structures with various types of friction brakeswhich inhibit such flop. These friction brakes suffer from one or moreof the drawbacks of requiring frequent adjustment, of requiring thejoint structure to be disassembled for servicing brake parts, of lackingflexibility for modifications for changing braking capacity, and ofhaving the braking surfaces arranged such that dirt, lubricants andother foreign substances come into contact therewith and diminish thelife and/or effectiveness thereof.

SUMMARY OF THE INVENTION

According to the present invention, there is provided an improvedbraking means embodied in a grapple pivot joint structure.

A broad object of the invention is to provide a grapple pivot jointstructure which embodies a brake comstructed so as to overcome theaforementioned drawbacks of the prior art.

More specifically, it is an object of the invention to provide a grapplepivot structure including brakes having friction elements located inhousings at the outer ends of the pivot pins of the axes so as to bereplaceable without disassembling the pins.

Another object of the invention is to provide a grapple pivot pinstructure including lubricated bearings and having a brake isolated fromthe lubricant applied to the bearings.

These and other objects will become apparent from a reading of thedescription together with the appended drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a left rear perspective view of a forestry grapple skidderhaving a grapple suspended from a boom by a pivot joint structureembodying friction brakes constructed in accordance with the principlesof the present invention.

FIG. 2 is a side elevational view of the grapple suspension taken alonga first pivot axis and having a portion of the pivot joint structure ofthe second pivot shown in vertical section so as to show the interior ofone of the brakes, the upper and lower halves of the sectionrespectively illustrating the brake housing access plate in a loosenedand fully installed position.

FIG. 3 is a side elevational view taken of the grapple suspension takenalong the second pivot.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1, therein is shown a grapple skidder 10 includingfront and rear wheel-supported frame sections 12 and 14, respectivelyinterconnected by a vertical pivot assembly (not shown). The front framesection carries an engine enclosed at 16 and an operator's station withattendant controls at a location 18 rearwardly of the enclosed engine.

The rear frame section has a grapple structure 20 mounted thereon.Specifically, the grapple structure 20 includes an inverted Y-shapedsupport boom 22 having an inner or lower end defined by a pair oftransversely spaced legs connected to the frame section 14, as at 23,(only right side visible) for swinging vertically about a horizontaltransverse axis. Hydraulic actuators 24 and 26 are connected between theframe section 14 and the boom 22 for controlling the vertical movementof the latter. A grapple 28 is suspended from the upper or outer end ofthe boom 22 by a suspension 32 which incorporates the present invention.

As can best be seen in FIGS. 2 and 3, the boom 30 carries an uprightshaft 33 having a pair of transversely spaced depending lugs 34 and 36at its lower end and respectively located between upwardly projectinglugs 38 and lugs 40, the lugs 38 and 40 forming part of a swivel link42. Each of the lugs 34, 36, 38 and 40 is provided with a bore and thesebores are arranged in alignment with each other along a first horizontalaxis X--X.

Located in the bore means defined by the bores in the lug 36 and the setof lugs 40 is a pivot pin 44, which forms part of a friction brake. Thepivot pin 44 has a series of sections, which increase in diameter fromthe inner to the outer end of the pin. Specifically, the pin 44 includesan inner bearing section 46 followed by a splined mounting section 48,an outer bearing section 50, a narrow section 52 and a splined outersection 54. The inner and outer bearing sections 46 and 50 arerespectively received in bushings 56 and 58 pressed into the bores ofthe set of lugs 40 while the splined mounting section 48 is received inand engaged with splines provided in the bore of the lug 36. A brakehousing 60 encloses the narrow and splined outer sections 52 and 54 andincludes an inner plate 62 provided with a bore in which the narrow andouter bearing portions of the pin 44 are partly received. The plate 62further includes three ears, indicated collectively at 64, spacedequidistant from and equiangularly about the pivot pin 44 at a locationbelow the pin and secured to the swivel link 42 by three capscrews 66received in respective bores provided in the ears 64. The plate 62additionally includes an annular outwardly projecting rim 68 disposedcoaxially with the pin 44 and the brake housing 60 includes an access orcover plate 70 engaged with the outer end of the pin 44 and releasablysecured to the rim 68 by a set of four cap screws 72. Thus, it will beappreciated that inasmuch as the housing 60 is held in place by the capscrews 64 and the access plate 70 is against the outer end of the pin44, the latter is held in place by the housing.

Located within the housing 60 is a stack of brake disks including afirst pair of disks 74 having friction material fixed to opposite facesthereof and a second pair of disks 76 which serve as pressure plates.The disks 74 have splined central openings engaged with the splines onthe splined outer section 54 of the pin 44 so as to be axially shiftablealong but no rotatable about the pin. The disks 76 are each providedwith four equiangularly spaced protuburances 78 (only one shown) abouttheir periphery and these protuberances are respectively received infour equispaced pockets 80 formed in the rim 68 of the housing so as tobe axially shiftable but not rotatable within the housing 60. It isnoted that one of the disks 74 is located between the housing accessplate 70 and one of the disks 76. Mounted on the narrow section 52 is aBelleville spring 82, which, when unloaded as shown in the top half ofthe section illustrated in FIG. 2, is dished outwardly so that its innerperiphery engages the plate 62 of the housing 60 and its outer peripheryengages the inner one of the pair of disks 76. When the cap screws 72are tightened, the Belleville spring 82 is deflected so as to becomesandwiched flat between the plate 62 and the disc 76 so as to maintainthe stack of brake disks 74 and 76 in biased engagement with each otherto thereby maintain a constant braking action resisting swingingmovement of the swivel joint 42 about the axis X--X. While the narrowsection 52 could be located outwardly of the splined section 54 of thepin 44 with the Belleville spring 82 then being mounted between theaccess cover 70 and the stack of brake disks, the illustrated embodimentis preferred since the Belleville spring 82 is then positioned and thestack of disks arranged so as to prevent the inner one of the stack ofbrake disks from falling off the splined section 54 of the pin duringassembly.

A lubricant passage 84 is located in the pin 44 and includes two sets ofradial openings 86 and 88, which respectively convey lubricant to thebushings 56 and 58. A grease fitting 90 at the inner end of the pin 44is screwed into an axial portion of the passage 84. Located on the outerbearing section 50 of the pin 44 just outwardly of the bushing 58 is aseal 92, which serves to prevent lubricant from entering the brakehousing 60.

The mounting of the swivel joint 42 to the shaft 33 is completed by apivot pin 94, which is received in a bore means located on the axis X--Xand defined by bores provided in the lug 34 and set of lugs 38. Thepivot pin 94 is held in place by a retaining pin 96 which extendsthrough a drilled passage provided in a boss 98 formed integrally withthe outer one of the set of lugs 38 and a cross passage provided in anouter portion of the pin 94.

It is to be understood that in cases where additional braking capacityis required, the right side of the swivel joint (FIG. 2) may be modifiedand a brake assembly of the sort described hereinabove may be used tojoin the right side of the swivel joint to the shaft 33.

The lower end of the swivel joint 42 is defined, as viewed in FIG. 3, byright- and left-hand lugs 100 and 102. The grapple 28 includes a head ortong support frame 104 defining a right pair of lugs indicated at 106and having the lug 100 disposed therebetween and a left pair of lugsindicated at 108 and having the lug 102 disposed therebetween. The lugs100, 102, 106 and 108 are provided with axially aligned bores arrangedalong an axis Y--Y disposed crosswise to the axis X--X. Located in thebore means defined by the bores in the lugs 100 and 106 is a pivot pin110, which is similar to construction and mounted similarly to the pin44 described hereinabove. The pin 110 has a right end portion (notshown) enclosed by a brake housing 112, which is secured to the grapplehead 104 by cap screws 114. Enclosed by the housing 112 are two sets ofbrake disks (not shown), which are respectively constructed similarly tothe sets of disks 74 and 76 described above and are respectivelynon-rotatably connected to the pin 110 and housing 112.

The bore means defined by the bores in the lugs 102 and 108 have a pivotpin 116 received therein and held in place by a locking pin 118 receivedin a cross bore in the left end portion of the pin and in a boreprovided in a boss 120 formed integrally with the outer one of the setof lugs 108.

The operation of the grapple suspension is as follows. During transportof the grapple skidder 10 in the forest, when the grapple 28 is unloadedas shown in FIG. 1, the tires in following uneven terrain and in passingover obstacles such as logs and boulders will create motion in the rearframe section 14 which will tend to effect swinging of the grapple aboutthe axes X--X and Y--Y. Motion about the axis X--X is frictionallyresisted by the stack of brake disks 74 and 76 which are loaded intoengagement with each other by the Belleville spring 82 so that motionwhich does occur is very slow. Motion about the axis Y--Y is similarlyfrictionally resisted. The frictional resistance to motion about theaxis of X--X and Y--Y may be changed, as desired, by varying the orderand number of disks 74 and 76 to provide different combinations offriction surfaces.

In the event that the motion about the axes X--X and Y--Y is notsufficiently restrained by a given pivot pin and associated brakestructure, a pivot pin having a longer outer splined end portion may beused along with additional disks 74 and 76 for added capacity. Of coursea completely new housing 60 or at least a different cover 70 would thenhave to be provided to accommodate the longer splined end section of thepivot pin.

Another way of providing additional braking capacity would be to providea suspension wherein the pin 94 on the axis X--X and the pin 116 on theaxis Y--Y are respectively replaced by a pivot pin and associatedfriction brake constructed similarly to the pins 44 and 110 and theirassociated friction brakes.

In the event that the brake disks of the grapple suspension 32 shouldbecome worn to the extent that adequate braking no longer occurs, thedisks may be easily replaced without necessitating the removal of thepins 44 or 110. For example, with reference to FIG. 2, it can be seenthat the disks 74 and 76 may be replaced by merely removing the accesscover 70 and taking out the worn disks 74 and 76. New disks 74 and 76may then be installed in place and the cover 70 reinstalled. As thescrews 72 are being tightened to move the cover 70 from its looseposition shown in the top half to its closed position shown in thebottom half of the illustration, the Belleville spring 82 moves from itsillustrated uncompressed to its fully compressed position. Thus, oncethe cover 70 is properly installed the spring 82 will be properlycompressed.

I claim:
 1. A pivot joint assembly incorporating a friction brake,comprising: first and second members respectively defining first andsecond axially aligned bores; a pivot pin received in the first andsecond bores; first means securing the pivot pin to the first member;said second member being rotatably received on the pin; said pinincluding an end portion located outside the first and second bores; ahousing encompassing said end portion and being fixed solely to thesecond member; a friction brake located in said housing and including atleast one pressure plate non-rotatably and axially shiftably mounted onthe pin and a friction plate non-rotatably mounted in the housing; and aBelleville spring compressed between the housing and the pressure plate.2. The pivot joint assembly defined in claim 1 wherein the housingincludes a cover plate located in axial alignment with the pin and thefriction brake and being releasably secured to the remainder of thehousing, said friction brake being sandwiched between the Bellevillewasher and the cover plate and compressively loaded by the Bellevillewasher when the cover plate is installed.
 3. The pivot joint assemblydefined in claim 1 wherein the first means securing the pivot pin to thefirst member comprises mating splined portions respectively located inthe first bore and on the pivot pin.
 4. The pivot joint assembly definedin claim 1 wherein the second member includes a pair of lugs providedrespectively with a pair of bore portions which define the second boreand the first member includes a lug disposed between the pair of lugsand having the first bore located therein in axial alignment with thealigned bore portions; a pair of bushings respectively being press fitin the pair of bore portions; said pivot pin having a pair of bearingsurfaces respectively pivotally received in the pair of bushings; alubrication passage means being provided in the pivot pin and leading tothe pair of bushings; and a lubricant seal mounted on the pin betweenthe bushings and the friction brake so as to isolate the latter fromlubricant used to lubricate the bushings.
 5. In a grapple suspensionincluding a swivel link respectively pivotally connected to a supportboom and a grapple head by first and second pivot pin means arrangedcrosswise to each other so as to define first and second pivot axes, animproved friction brake, comprising: said first and second pivot pinmeans respectively being non-rotatably fixed to the support boom and tothe swivel link; the first pivot pin means including an end portionlocated beside the swivel link; a first brake disk non-rotatably mountedon the end portion of the first pivot pin means; a brake housingenclosing the end portion of the first pivot pin means and integrallyfixed to the swivel link; a second brake disk located in the brakehousing and non-rotatably mounted thereto in a location adjacent thefirst brake disk; and a Belleville spring located in the brake housingand compressed between a wall of the latter and one of the first andsecond brake disks.
 6. The grapple suspension defined in claim 5 whereinthe support boom includes a downwardly projecting lug provided with asplined bore arranged along the first axis and the swivel link includesfirst and second upwardly projecting lugs respectively provided withfirst and second bores arranged along the first axis; said first pivotpin means including a first pivot pin having first and second bearingportions received in the first and second bores and a first splinedportion received in the splined bore; said end portion of the pivot pinbeing considerably larger in diameter than the remainder thereof andbeing defined by a second splined portion; and said first brake diskhaving splines received on the second splined portion.
 7. The grapplesuspension defined in claim 6 wherein said first pivot pin is providedwith a lubricant passage leading to the first and second bearingportions thereof; and a lubricant seal being located on the first pinbetween the brake housing and an adjacent one of the bearing portions.8. The grapple suspension defined in claim 6 wherein the first pivot pinincludes an annular surface portion located between the second splinedportion and an adjacent one of the first and second bearing portions,the annular surface portion being smaller in diameter than the secondsplined portion and being located at least partly within the housing;and said Belleville spring being received on the annular surface.
 9. Thegrapple suspension defined in claim 8 wherein the brake housing includesa removable access cover located at that end of the first pivot pindefined by the second splined portion and extending axially so as tohave the second splined portion received partly therein by apredetermined axial amount when the cover is installed; saidpredetermined axial amount being at least equivalent to an axialdeflection of the Belleville spring required to move the latter betweenfree and fully compressed conditions; and said first and second brakedisks being held in engagement with each other and the Belleville springbeing fully compressed when the cover is installed and the disks are inan unworn condition.